Bull, Soc, Chim, Frame, 1961, p1195–1198, discloses, as a process for synthesizing a 1-acetoxy-3-(substituted phenyl)propene compound, a process for synthesizing 1-acetoxy-3-(3,4-dimethoxyphenyl)propene by reacting 1,2-dimethoxybenzene with an alkenylidene diacetate in the presence of titanium tetrachloride activated with a boron trifluoride-ether complex. This literature reported that the yield of the target compound produced by this process was 62%, which was unsatisfactory. The inventors of the present invention tried to trace the process of the above-mentioned literature, and as a result, found that the yield of the target compound was only 12%, a plurality of by-products were produced, and the resultant product mixture liquid exhibited a brown color (refer to Comparative Example 3 of the present application). Also, it was confirmed that titanium tetrachloride, used for the process of the literature, was a chemically unstable compound to such an extent that this compound is decomposed by moisture in the atmospheric air, and thus complicated and meticulous care is needed in handling this compound.
Further, the inventors of the present invention tried to apply the process of the literature to the reaction of 3,4-methylenedioxy benzene with an alkenylidene diacetate and found that the titanium tetrachloride activated by boron trifluoride-ether complex caused a decomposition reaction of 3,4-methylenedioxybenzene to be promoted, and the yield of the target compound was 43% and unsatisfactory (refer to Comparative Example 1 of the present application). Furthermore, the inventors of the present invention tried to effect the reaction by using titanium tetrachloride in an amount of 0.1 mole per mole of alkenylidene diacetate, to control or prevent the decomposition of 3,4-methylenedioxybenzene. As a result, the yield of the target compound decreased to 9.8% (refer to Comparative Example 2 of the present application).
Japanese Unexamined Patent Publication No. 55–141437 discloses a process for producing 1-acetoxy-2-methyl-3-(4-t-butylphenyl)propene by reacting t-butylbenzene with methacrolein and acetyl chloride in the presence of a stoichiometric amount of a Lewis acid. In this process, when titanium tetrachloride was used as Lewis acid, the yield of the target compound was 46.2%, and when boron trifluoride-ether complex was employed as a Lewis acid, the yield of the target compound was 2.3%. In each of the above-mentioned cases, the target compound yield was low and unsatisfactory.